Sleep disorders are considered a large but under-diagnosed problem in society today. There are over seventy different sleep disorders that are believed to contribute to a range of health and social problems. Insufficient quality sleep is thought to be a contributing factor in many work- and car-related accidents and to many common health problems such as hypertension, depression, cardiovascular disease, diabetes, and kidney disease. Thus, sleep disorders are thought to have a significant health and economic impact on society.
The most common disorder is Obstructive Sleep Apnea (OSA) Syndrome. OSA is a sleep and breathing disorder where the upper airway partially or completely occludes during sleep. The presence of OSA Syndrome is defined as at least five obstructed breathing episodes per hour of sleep together with daytime sleepiness symptoms. Some studies estimate that OSA Syndrome affects approximately 2-4% of the general population. There are a number of factors that increase the risk of OSA Syndrome including age, sex, and weight. The prevalence in males and females over 30 years of age may be closer to 24% and 9% respectively. Thus, this disorder has a significant impact on society. However, the diagnosis and treatment rates for this disorder currently are very low.
Excess tissue in the upper airway and physical abnormalities worsen OSA. During sleep, especially in REM sleep, our bodies relax, and muscle tissues like the tongue and soft palate lose their slight rigidity, and the airway collapses. When these tissues obstruct the upper airway completely, they prevent breathing and can actually begin to suffocate the sleeper. The sleeper wakes up enough to regain control of the upper airway, breathes again, and then falls back to sleep. This happens from dozens to hundreds of times per night for people with OSA, but they usually do not remember waking up.
Each obstruction deprives the body of oxygen and does not allow it to get rid of carbon dioxide that it would normally exhale. When the body sets off “alarms” that it needs more oxygen, the brain wakes the sleeper, breathing resumes, and the individual falls back asleep until the next obstruction occurs. These obstructions increase heart rate, raise blood pressure, and eventually blunt the body's automatic response system, allowing increasingly more severe apneas and hypopneas.
OSA may have a significant impact on an individual's health. Because of the disruption in sleep, a common symptom of OSA is daytime sleepiness. Daytime sleepiness may impact an individual's performance and/or ability to control machinery. For example daytime sleepiness caused by OSA may impair an individual's ability to drive a car and may be a factor in car accidents.
The current method of treatment for OSA is positive airway pressure (PAP) delivered to an individual's airways while they are asleep. Colin Sullivan was the first to invent the use of nasal Continuous Positive Airway Pressure (CPAP) to treat Obstructive Sleep Apnea (OSA). See U.S. Pat. No. 4,944,310. The treatment generally provides a continuous supply of air or breathable gas from a blower or flow generator to a patient via an air delivery conduit and a patient interface, such as a full-face or nasal mask or nasal prongs. The air or breathable gas is commonly delivered at a pressure of 4-20 cmH20 and acts as a splint to hold the airway open during sleep
Further developments of CPAP have provided automatically adjusting devices that a patient could take home. The automatically adjusting device will raise and/or lower the treatment pressure based on indications of OSA, such as snoring. Such CPAP devices sometimes generically are referred to as Automatic Positive Airway Pressure (APAP) devices. An example of an APAP device is the ResMed Autoset® Spirit™. See U.S. Pat. Nos. 5,245,995; 6,398,739; and 6,635,021.
Another type of nasal CPAP device provides a first pressure during inhalation (typically termed IPAP) and a second, lower pressure during exhalation (typically termed EPAP). Examples of these include the ResMed VPAP™ series, and the Respironics BiPAP series. Bilevel CPAP devices may be prescribed for patients who do not comply with single pressure CPAP devices. Some patients perceive that the lower pressure during exhalation is more comfortable, at least while they are awake.
The current diagnosis and treatment process for OSA generally begins when an individual or their bed partner complains of daytime sleepiness or excess snoring. In this scenario, the individual would visit a GP for a referral to a sleep specialist. The individual would then make an appointment to visit the sleep specialist who would review the patient's symptoms and refer them to a sleep laboratory for diagnosis by polysomnography (PSG). For diagnosis and a treatment plan to be established, an individual generally needs to spend two nights in the sleep laboratory, with the first night being for diagnosis and the second night being for therapy titration.
Therapy titration identifies the correct treatment pressure required by the individual to overcome OSA, such that apneas are eliminated. The treatment pressure is usually in the range of 4-20 cmH20. Following diagnosis and therapy titration, an individual may purchase an appropriate therapy device that is set to the identified treatment pressure.
Unfortunately, this process is time consuming and expensive. There are often extensive waiting periods, from four weeks to two years or more, for a PSG at a sleep laboratory, with each PSG study costing in excess of $750. Also, the system relies on the individuals recognizing the symptoms and seeking medical advice. Currently, the awareness level of this disorder is low, which impacts the recognition of symptoms, diagnosis, and ultimately treatment.
There are also a number of portable Diagnostic Systems (PDS) currently available, such as the FLAGA Embletta® and the ApneaLink™ devices. These devices comprise data recorder units that generally are strapped around the patients' torso. A range of sensor components are connected to the data recorder units to deliver information relating to a range of sleep parameters, such as the pressure, air flow, oxygen saturation level, position, and sleep stage. However, these systems are uncomfortable for the wearer for a number of reasons. For example, the wires inhibit the wearers while they are trying to sleep, and the data recorder unit is relatively large and bulky, also inhibiting the wearers while the wearers are trying to sleep. Because of this discomfort, the results obtained by the systems sometimes are considered to be unreliable, as they do not accurately record a typical night's sleep for the patient.
More recently, there have been monitoring and sensing shirts designed that have sensors incorporated within their fibers, such as the Vivometrics® LifeShirt® (http://www.vivometrics.com) and the SensaTex™ SmartShirt (http://www.sensatex.com). The LifeShirt® eliminates many of the wires, but not the data recorder unit. The SensaTex™ SmartShirt attempts to eliminate both the wires and the data recorder through integrated electronic textile solutions.
The patents mentioned herein are hereby incorporated herein by reference in their entireties.